Here below a small trick to recognize if a site has been created with the Joomla CMS.
You can open the site in fact with the option tp=1 in the URL: you will be able to see all the various boxes for modules (depending on the template).
Try this link to see an example with this site.

If the boxes will also be transparent (having of course a recent and capable browser) you are sure have found a 1.5.x joomla version; otherwise it will probably be a 1.0.x version.